<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<script>
			var num1 = parseInt(prompt("请输入第一个整数："));
			var num2 = parseInt(prompt("请输入第二个整数："));
			var num3 = parseInt(prompt("1.+ 2.- 3.* 4./"));

			if (num3==1){
				alert(num1 + num2);
			}else if (num3==2){
				alert(num1 + num2);
			}else if (num3==3){
				alert(num1 + num2);
			}
			else if (num3==4){
				alert(num1 + num2);
			}else{
				alert("错误！");
			}
		</script>
	</body>

</html>